Re: st: --svy & --pweights: problems for median, graphs & regression

Thanks heaps, Steve!
Also for correcting the way I wrote commands...
hafida--
Nur Hafidha Hikmayani
School of Medicine & Public Health
The University of Newcastle
Australia
----- Original Message -----
From: Steven Samuels <sjhsamuels@earthlink.net>
Date: Thursday, September 11, 2008 2:07 pm
Subject: Re: st: --svy & --pweights: problems for median, graphs & regression
> Hafida
>
>
>
> a. Look at -help- for -pctile- and -_pctile-. These take pweights
>
> b. -histogram- will take fweights, but not pweights: See http://
> www.stata.com/statalist/archive/2007-10/msg00327.html and preceding
>
> messages in the thread.
>
> c. -svy: reg- automatically computes standard errors that are
> robust
> to heteroskedasticity. Homogeneity of variance is not an assumption
>
> for survey tests of means or regression coefficients.
>
> d. See: http://www.stata.com/statalist/archive/2007-
> 12/msg00621.html
> to compute an adjusted R-square with survey data. You should
> consider other measures of fit, such as -linktest-.
>
> e. No--not if you want to believe the standard errors and tests.
> However you might be able to test hypotheses about single-outcome
> survey regressions with -suest-.
>
> To use the survey-enabled programs like -svy: reg- for inference
> (hypothesis, confidence intervals, standard errors) you must first -
>
> svyset- your data. -svyset- will allow you to account for the
> entire
> sampling design, not just weighting.
>
>
> For future reference the appropriate way to refer to Stata commands
>
> in the list is with hyphens around them" "-manova-" , not "--manova"
>
>
> -Steve
>
> On Sep 11, 2008, at 12:59 AM,
> Nur.Hikmayani@studentmail.newcastle.edu.au wrote:
>
> > Hi all,
> >
> > I have 4 continuous DVs (quality of life domains of SF-36: GH,
> PF,
> > MH, SF) which are moderately inter-correlated (0.5) and two of
> them
> > have skewed distributions. I originally intended to use --manova
> &
> > --mvreg until lately when I realised that I'm using a dataset
> from
> > a survey with over-sampling for participants living in remote
> > areas. The dataset had had a weighted variable already so have to
>
> > take this into account. To some extent, this had affected the
> > statistical method I'd like to use previously. So far, I've
> > performed a separate analysis for each DV as I have no idea on
> how
> > to apply --svy nor --pw to --manova and --mvreg.
> >
> > Some of my concerns are:
> > a. I need descriptives other than mean & proportion, particularly
>
> > for skewed DVs which I think median or percentiles is more
> > appropriate. While --svy does not support this, is there a way to
>
> > get the estimates?
> > b. How to create histogram for weighted mean DV as this will help
>
> > get a sense if assumption for normality for an OLS regression is
> met?> c. When using --regress with --svy to get ANOVA, how is
> homogeneity
> > of variance assessed?
> > d. I noticed that there is no adjusted R-squared when using --
> svy,
> > so is it appropriate to build a model using R-squared instead?
> > e. Lastly, if it's not impractical at all, is it still possible
> to
> > run --mvreg and take weights into account?
> >
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